1. Field of the Invention
The present invention relates to a syringe device fixable on a flask, in particular a flask containing a liquid to be injected or a substance that has been lyophilized and that is to be mixed with a physiological liquid or with medication so that the mixture can be injected.
2. Description of Related Art
There exist known substances, particularly in the medical field, which need to be stored separately and which should be mixed only immediately prior to being injected into a patient, e.g. subcutaneously, intravenously, or into muscle. This applies in particular to medical substances which are prepared in lyophilized (freeze dried) form, or in powder form, and which need to be mixed with a solvent, e.g. physiological serum, for administration to a patient. In other cases, the two components that are mixed together may both be liquids, when the liquids cannot be stored for long periods of time when mixed together.
The most commonly used technique is to store the powder in a separate receptacle which is closed by a membrane or a leakproof plug that can be punctured by means of a needle. Then, using a syringe of standard type, a certain quantity of solvent is taken from a second receptacle and the appropriate quantity of solvent is injected into the first receptacle through the membrane. The content of the first receptacle is then mixed together and the same syringe is then used to suck up the mixture. The syringe is then ready for injecting the medication.
In other known techniques, the liquid, e.g. physiological serum, is already contained in the syringe. It then suffices to inject the liquid through the puncturable membrane into the receptacle containing the substance in powder form, to mix the substances together, and then suck the mixture back into the syringe.
However, that technique suffers from certain difficulties in use. In particular, when the flask containing the powder has a neck of small diameter, it is difficult to puncture the puncturable plug appropriately. An essential condition for extracting all of the liquid contained in the flask after the powder has been mixed with the solvent is for the puncturable plug to be punctured in its center and for the needle to be inserted as small a distance as possible into the flask. That also serves to avoid wetting the needle while mixing is being performed, thus leaving the needle in a condition suitable for being reused to inject the mixture into the patient. Unfortunately, as already mentioned, when the neck of the flask is of small diameter, this can be difficult to do. There also exists a non-negligible risk of the user, e.g. a nurse, pricking a finger while performing the above operation.
An object of the present invention is to provide a syringe device that is fixable on a flask and which ensures that the puncturable plug is punctured in its center and which also makes this operation very reliable and completely repeatable. Another object of the present invention is to provide such a device which can be fitted onto a flask commonly used for containing medicinal powders for mixing with a solvent, and in particular substances that have been lyophilized.